gmwso vs viditchess

White pushed the b‑pawn from b4 to b5. The move creates a passed pawn on the queenside, keeps the queen on c5 eyeing the defended d5 pawn, and forces Black to react to the new pawn threat. After 43.b5 the immediate material balance is unchanged, but Black's most dangerous threat – …h3×h3 – remains, while White's own h3 pawn stays undefended.

The engine marks 43.b5 as the optimal continuation because it generates a second front that Black must answer. The pawn advance forces Black's queen off the defence of the d5 pawn (the engine’s best reply is 43…Qf5), and it also limits the black king’s escape squares on the queenside. Any alternative, such as a quiet move like 43.Qd5, would allow Black to consolidate with …Qf5 and maintain the h‑pawn menace. By playing b5, White gains a passed pawn that can march to b6‑b7‑b8=Q, while still retaining the pressure on d5, thereby converting the positional advantage into a concrete winning chance.

Create a Passed Pawn to Generate Dual Threats: In endgames, advancing a pawn that becomes a passed pawn forces the opponent to split their defensive resources, often turning a static advantage into a decisive one.